title: A study of wall shear stress in 12 aneurysms with respect to different viscosity models and flow conditions.
abstract: Recent computational fluid dynamics (CFD) studies relate abnormal blood flow to rupture of cerebral aneurysms. However, it is still debated how to model blood flow with sufficient accuracy. Common assumptions made include Newtonian behaviour of blood, traction free outlet boundary conditions and inlet boundary conditions based on available literature. These assumptions are often required since the available patient specific data is usually restricted to the geometry of the aneurysm and the surrounding vasculature. However, the consequences of these assumptions have so far been inadequately addressed. This study investigates the effects of 4 different viscosity models, 2 different inflow conditions and 2 different outflow conditions in 12 middle cerebral artery aneurysms. The differences are quantified in terms of 3 different wall shear stress (WSS) metrics, involving maximal WSS, average WSS, and proportion of aneurysm sac area with low WSS. The results were compared with common geometrical metrics such as volume, aspect ratio, size ratio and parent vessel diameter and classifications in terms of sex and aneurysm type. The results demonstrate strong correlations between the different viscosity models and boundary conditions. The correlation between the different WSS metrics range from weak to medium. No strong correlations were found between the different WSS metrics and the geometrical metrics or classifications.
authors.affiliation: Center for Biomedical Computing, Simula Research Laboratory, Martin Linges vei 17, Fornebu, Norway.
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Evju
authors.forename: Kristian
authors.initials: K
authors.lastname: Valen-Sendstad
authors.forename: Kent-André
authors.initials: KA
authors.lastname: Mardal
mesh_terms: D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology*; D001783:Blood Flow Velocity; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006400:Hematocrit; D006439:Hemodynamics; D006801:Humans; D057446:Hydrodynamics; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008955:Models, Cardiovascular; D011673:Pulsatile Flow; D012039:Regional Blood Flow; D012737:Sex Factors; D033081:Shear Strength; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed; D014783:Viscosity
keywords: Boundary conditions; Cerebral aneurysms; Computational fluid dynamics; Non-Newtonian fluid; Wall shear stress